Autophagy Contributes to the Death/Survival Balance in Cancer PhotoDynamic Therapy

Autophagy Regulation Using Multimodal Chlorin e6-Loaded Polysilsesquioxane Nanoparticles to Improve Photodynamic Therapy

Photodynamic therapy (PDT) is a promising anticancer noninvasive technique that relies on the generation of reactive oxygen species (ROS). Unfortunately, PDT still has many limitations, including the resistance developed by cancer cells to the cytotoxic effect of ROS. Autophagy, which is a stress response mechanism, has been reported as a cellular pathway that reduces cell death following PDT. Recent studies have demonstrated that PDT in combination with other therapies can eliminate anticancer resistance. However, combination therapy is usually challenged by the differences in the pharmacokinetics of the drugs. Nanomaterials are excellent delivery systems for the efficient codelivery of two or more therapeutic agents. In this work, we report on the use of polysilsesquioxane (PSilQ) nanoparticles for the codelivery of chlorin-e6 (Ce6) and an autophagy inhibitor for early- or late-stage autophagy. Our results, obtained from a reactive oxygen species (ROS) generation assay and apoptosis and autophagy flux analyses, demonstrate that the reduced autophagy flux mediated by the combination approach afforded an increase in the phototherapeutic efficacy of Ce6-PSilQ nanoparticles. We envision that the promising results in the use of multimodal Ce6-PSilQ material as a codelivery system against cancer pave the way for its future application with other clinically relevant combinations.

IMMUNEPOTENT CRP increases intracellular calcium through ER-calcium channels, leading to ROS production and cell death in breast cancer and leukemic cell lines

IMMUNEPOTENT CRP (ICRP) is an immunotherapy that induces cell death in cancer cell lines. However, the molecular mechanisms of death are not completely elucidated. Here, we evaluated the implication of intracellular Ca²⁺ augmentation in the cell death induced by ICRP on T-ALL and breast cancer cell lines. Cell death induction and the molecular characteristics of cell death were evaluated in T-ALL and breast cancer cell lines by assessing autophagosome formation, ROS production, loss of mitochondrial membrane potential, ER stress and intracellular Ca²⁺ levels. We assessed the involvement of extracellular Ca²⁺, and the implication of the ER-receptors, IP₃R and RyR, in the cell death induced by ICRP, by using an extracellular calcium chelator and pharmacological inhibitors. Our results show that ICRP increases intracellular Ca²⁺ levels as the first step of the cell death mechanism that provokes ROS production and loss of mitochondrial membrane potential. In addition, blocking the IP₃ and ryanodine receptors inhibited ER-Ca²⁺ release, ROS production and ICRP-induced cell death. Taken together our results demonstrate that ICRP triggers intracellular Ca²⁺-increase leading to different regulated cell death modalities in T-ALL and breast cancer cell lines. See also Figure 1(Fig. 1).

Self-delivery biomedicine for enhanced photodynamic therapy by feedback promotion of tumor autophagy

Reactive oxygen species (ROS) generated during photodynamic therapy (PDT) can induce autophagy to protect tumor cell from PDT-induced apoptosis. In this work, a self-delivery autophagy regulator (designated as CeCe) is developed for autophagy promotion sensitized PDT against tumor. Briefly, CeCe is prepared by the assembly of a photosensitizer of chlorin e6 (Ce6) and autophagy promoter of celastrol. By virtue of intermolecular interactions, Ce6 and celastrol are able to self-assemble into nanomedicine with great photodynamic performance and autophagy regulation capacity. Under light irradiation, CeCe would produce ROS in tumor cells to amplify the oxidative stress and promote cell autophagy. As a result, CeCe exhibits an enhanced photo toxicity by inducing autophagic cell death. In vivo experiments indicate that CeCe can predominantly accumulate in tumor tissue for a robust PDT. Moreover, CeCe has a superior therapeutic efficiency compared to monotherapy and combined treatment of Ce6 and celastrol, suggesting a synergistic antitumor effect of PDT and autophagy promotion. This self-delivery nanomedicine may advance the development of the co-delivery nanoplatform to improve the antitumor efficacy of PDT by promoting autophagy. STATEMENT OF SIGNIFICANCE: Autophagy is a "double-edged sword" in cellular homeostasis and metabolism, which can promote tumor progression but also induce an unknown impact on tumor inhibition. In this work, a self-delivery autophagy regulator (designated as CeCe) was developed for autophagy promotion sensitized photodynamic therapy (PDT). By virtue of intermolecular interactions, Ce6 and celastrol were found to self-assemble into stable CeCe without drug excipients, which exhibited great photodynamic performance and autophagy regulation capacity. In vitro and in vivo findings demonstrated a superior tumor suppression ability of CeCe over the monotherapy as well as the combined treatment of Ce6 and celastrol, suggesting a synergistic antitumor efficacy by PDT and autophagy promotion.

The "Light Knife" for Gastric Cancer: Photodynamic Therapy

Photodynamic therapy (PDT) has been used clinically to treat cancer for more than 40 years. Some solid tumors, including esophageal cancer, lung cancer, head and neck cancer, cholangiocarcinoma, and bladder cancer, have been approved for and managed with PDT in many countries globally. Notably, PDT for gastric cancer (GC) has been reported less and is not currently included in the clinical diagnosis and treatment guidelines. However, PDT is a potential new therapeutic modality used for the management of GC, and its outcomes and realization are more and more encouraging. PDT has a pernicious effect on tumors at the irradiation site and can play a role in rapid tumor shrinkage when GC is combined with cardiac and pyloric obstruction. Furthermore, because of its ability to activate the immune system, it still has a specific effect on systemic metastatic lesions, and the adverse reactions are mild. In this Review, we provide an overview of the current application progress of PDT for GC; systematically elaborate on its principle, mechanism, and the application of a new photosensitizer in GC; and focus on the efficacy of PDT in GC and the prospect of combined use with other therapeutic methods to provide a theoretical basis for clinical application.

Anticancer Effects of Fucoxanthin through Cell Cycle Arrest, Apoptosis Induction, Angiogenesis Inhibition, and Autophagy Modulation

Cancer accounts for one in seven deaths worldwide and is the second leading cause of death in the United States, after heart disease. One of the standard cancer treatments is chemotherapy which sometimes can lead to chemoresistance and treatment failure. Therefore, there is a great need for novel therapeutic approaches to treat these patients. Novel natural products have exhibited anticancer effects that may be beneficial in treating many kinds of cancer, having fewer side effects, low toxicity, and affordability. Numerous marine natural compounds have been found to inhibit molecular events and signaling pathways associated with various stages of cancer development. Fucoxanthin is a well-known marine carotenoid of the xanthophyll family with bioactive compounds. It is profusely found in brown seaweeds, providing more than 10% of the total creation of natural carotenoids. Fucoxanthin is found in edible brown seaweed macroalgae such as Undaria pinnatifida, Laminaria japonica, and Eisenia bicyclis. Many of fucoxanthin's pharmacological properties include antioxidant, anti-tumor, anti-inflammatory, antiobesity, anticancer, and antihypertensive effects. Fucoxanthin inhibits many cancer cell lines' proliferation, angiogenesis, migration, invasion, and metastasis. In addition, it modulates miRNA and induces cell cycle growth arrest, apoptosis, and autophagy. Moreover, the literature shows fucoxanthin's ability to inhibit cytokines and growth factors such as TNF-α and VEGF, which stimulates the activation of downstream signaling pathways such as PI3K/Akt autophagy, and pathways of apoptosis. This review highlights the different critical mechanisms by which fucoxanthin inhibits diverse cancer types, such as breast, prostate, gastric, lung, and bladder development and progression. Moreover, this article reviews the existing literature and provides critical supportive evidence for fucoxanthin's possible therapeutic use in cancer.

Enhanced Photodynamic Therapy: A Review of Combined Energy Sources

Photodynamic therapy (PDT) has been used in recent years as a non-invasive treatment for cancer, due to the side effects of traditional treatments such as surgery, radiotherapy, and chemotherapy. This therapeutic technique requires a photosensitizer, light energy, and oxygen to produce reactive oxygen species (ROS) which mediate cellular toxicity. PDT is a useful non-invasive therapy for cancer treatment, but it has some limitations that need to be overcome, such as low-light-penetration depths, non-targeting photosensitizers, and tumor hypoxia. This review focuses on the latest innovative strategies based on the synergistic use of other energy sources, such as non-visible radiation of the electromagnetic spectrum (microwaves, infrared, and X-rays), ultrasound, and electric/magnetic fields, to overcome PDT limitations and enhance the therapeutic effect of PDT. The main principles, mechanisms, and crucial elements of PDT are also addressed.

Melatonin improves arsenic-induced hypertension through the inactivation of the Sirt1/autophagy pathway in rat

Arsenic (As), a metalloid chemical element, is classified as heavy metal. Previous studies proposed that As induces vascular toxicity by inducing autophagy, apoptosis, and oxidative stress. It has been shown that melatonin (Mel) can decrease oxidative stress and apoptosis, and modulate autophagy in different pathological situations. Hence, this study aimed to investigate the Mel effect on As-induced vascular toxicity through apoptosis and autophagy regulation. Forty male rats were treated with As (15 mg/kg; oral gavage) and Mel (10 and 20 mg/kg, intraperitoneally; i.p.) for 28 days. The systolic blood pressure (SBP) changes, oxidative stress markers, the aorta histopathological injuries, contractile and relaxant responses, the level of apoptosis (Bnip3 and caspase-3) and autophagy (Sirt1, Beclin-1 and LC3 II/I ratio) proteins were determined in rats aorta. The As exposure significantly increased SBP and enhanced MDA level while reduced GSH content. The exposure to As caused substantial histological damage in aorta tissue and changed vasoconstriction and vasorelaxation responses to KCl, PE, and Ach in isolated rat aorta. The levels of HO-1 and Nrf-2, apoptosis markers, Sirt1, and autophagy proteins also enhanced in As group. Interestingly, Mel could reduce changes in oxidative stress, blood pressure, apoptosis, and autophagy induced by As. On the other hand, Mel led to more increased the levels of Nrf-2 and HO-1 proteins compared with the As group. In conclusion, our findings showed that Mel could have a protective effect against As-induced vascular toxicity by inhibiting apoptosis and the Sirt1/autophagy pathway.

Assessing the bioavailability and biotoxicity of spiromesifen and its main metabolite spiromesifen-enol (M01) reveals the defense mechanisms of earthworms (Eisenia fetida)

As a promising acaricide and potentially hazardous material, the defense mechanisms of non-target organisms to its exposure are unknown. This study investigates the bioavailability and biotoxicity of spiromesifen and spiromesifen-enol (M01), its main metabolite, in Eisenia fetida. The results showed that M01 was more persistent in the soil environment and E. fetida than spiromesifen. Transcriptome analysis indicated that the spiromesifen- and M01-induced differentially expressed genes (DEGs) were mainly enriched in lysosomal and phagosomal pathways. Analysis of the key common DEGs showed that both spiromesifen and M01 significantly influenced the lysosomes, phagosomes, antioxidant systems, and detoxification systems. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that spiromesifen and M01 damaged E. fetida epidermis and enhanced lysosomal and phagosomal activities. Significant oxidative stress effects were observed at the end of exposure. The hydroxyl free radical (·OH^-) content and neutral red retention time (NRRT) could serve as sensitive early biomarkers to predict their pollution. These results revealed the synergistic effects of the epidermis, lysosomes, phagosomes, antioxidant systems, and detoxification system in resisting spiromesifen- and M01-induced damage, which could contribute to the defense mechanisms of non-target organisms against these pollutants.

Photodynamic treatment modulates various GTPase and cellular signalling pathways in Tauopathy

The application of photo-excited dyes for treatment is known as photodynamic therapy (PDT). PDT is known to target GTPase proteins in cells, which are the key proteins of diverse signalling cascades which ultimately modulate cell proliferation and death. Cytoskeletal proteins play critical roles in maintaining cell integrity and cell division. Whereas, it was also observed that in neuronal cells PDT modulated actin and tubulin resulting in increased neurite growth and filopodia. Recent studies supported the role of PDT in dissolving the extracellular amyloid beta aggregates and intracellular Tau aggregates, which indicated the potential role of PDT in neurodegeneration. The advancement in the field of PDT led to its clinical approval in treatment of cancers, brain tumour, and dermatological acne. Although several question need to be answered for application of PDT in neuronal cells, but the primary studies gave a hint that it can emerge as potential therapy in neural cells.

Nanozyme with Robust Catalase Activity by Multiple Mechanisms and Its Application for Hypoxic Tumor Treatment

Utilizing catalase-mimicking nanozymes to produce O₂ is an effective method to overcome tumor hypoxia. However, it is challenging to fabricate nanozymes with ultrahigh catalytic activity. Palladium nanosheet (Pd NS), a photothermal agent for photothermal therapy (PTT), has superior catalase-mimicking activity. Here, titanium dioxide (TiO₂ ) is used to modify Pd NS (denoted Pd@TiO₂ ) by a simple one-step method to improve its catalytic activity about 8 times. The enhancement mechanism's fundamental insights are discussed through experiments and density functional theory calculations. Next, zinc phthalocyanine is loaded on Pd@TiO₂ to form a nanomotor (denoted PTZCs) with the synergistic activities of photodynamic therapy and PTT. PTZCs inherit the catalase activity of Pd@TiO₂ to facilitate the decomposition of endogenous H₂ O₂ to O₂ , which can relieve tumor hypoxia and propel PTZC migration to expand the reach of PTZCs, further enhancing its synergistic treatment outcome both in vitro and in vivo. It is proposed that this work can provide a simple and effective strategy for catalytic activity enhancement and bring a critical new perspective to studying and guiding the nanozyme design.

Monoethanolamine-induced glucose deprivation promotes apoptosis through metabolic rewiring in prostate cancer

Rationale: Cancer cells rely on glucose metabolism for fulfilling their high energy demands. We previously reported that monoethanolamine (Etn), an orally deliverable lipid formulation, reduced intracellular glucose and glutamine levels in prostate cancer (PCa). Glucose deprivation upon Etn treatment exacerbated metabolic stress in PCa, thereby enhancing cell death. Moreover, Etn was potent in inhibiting tumor growth in a PCa xenograft model. However, the precise mechanisms underlying Etn-induced metabolic stress in PCa remain elusive. The purpose of the present study was to elucidate the mechanisms contributing to Etn-mediated metabolic rewiring in PCa.

Methods: Glucose transporters (GLUTs) facilitate glucose transport across the plasma membrane. Thus, we assessed the expression of GLUTs and the internalization of GLUT1 in PCa. We also evaluated the effects of Etn on membrane dynamics, mitochondrial structure and function, lipid droplet density, autophagy, and apoptosis in PCa cells.

Results: Compared to other GLUTs, GLUT1 was highly upregulated in PCa. We observed enhanced GLUT1 internalization, altered membrane dynamics, and perturbed mitochondrial structure and function upon Etn treatment. Etn-induced bioenergetic stress enhanced lipolysis, decreased lipid droplet density, promoted accumulation of autophagosomes, and increased apoptosis.

Conclusion: We provide the first evidence that Etn alters GLUT1 trafficking leading to metabolic stress in PCa. By upregulating phosphatidylethanolamine (PE), Etn modulates membrane fluidity and affects mitochondrial structure and function. Etn also induces autophagy in PCa cells, thereby promoting apoptosis. These data strongly suggest that Etn rewires cellular bioenergetics and could serve as a promising anticancer agent for PCa.

Curcumin-mediated photodynamic therapy inhibits the phenotypic transformation, migration, and foaming of oxidized low-density lipoprotein-treated vascular smooth muscle cells by promoting autophagy

Supplemental Digital Content is Available in the Text.

Vascular smooth muscle cells (VSMCs) are becoming a hot spot and target of atherosclerosis research. This study aimed to observe the specific effects of curcumin (CUR)-mediated photodynamic therapy (CUR-PDT) on oxidized low-density lipoprotein (ox-LDL)-treated VSMCs and confirm whether these effects are mediated by autophagy. In this study, the mouse aortic smooth muscle cell line and A7r5 cell lines were used for parallel experiments. VSMC viability was evaluated by Cell Counting Kit-8 assay. VSMCs were treated with ox-LDL to establish a model of atherosclerosis in vitro. The autophagy level and the expression of proteins related to phenotypic transformation were detected by western blotting. The migration ability of the cells was detected by using transwell assay. The presence of intracellular lipid droplets was detected by Oil Red O staining. The results showed that VSMCs transformed from the contraction phenotype to the synthetic phenotype when stimulated by ox-LDL, during which autophagy was inhibited. However, CUR-PDT treatment significantly promoted the level of autophagy and inhibited the process of phenotypic transformation induced by ox-LDL. In addition, ox-LDL significantly promoted VSMC migration and increased the number of lipid droplets, whereas CUR-PDT treatment significantly reduced the ox-LDL-induced increase in the migration ability of, and lipid droplet numbers in, VSMCs. When the VSMCs were pretreated with the autophagy inhibitor 3-methyladenine for 24 hours, the effects of CUR-PDT were reversed. Therefore, our study indicated that CUR-PDT can inhibit the phenotypic transformation, migration, and foaming of ox-LDL–treated VSMCs by inducing autophagy.

The human vault RNA enhances tumorigenesis and chemoresistance through the lysosome in hepatocellular carcinoma

The small non-coding VTRNA1-1 (vault RNA 1–1) is known to confer resistance to apoptosis in several malignant cell lines and to also modulate the macroautophagic/autophagic flux in hepatocytes, thus highlighting its pro-survival role. Here we describe a new function of VTRNA1-1 in regulating in vitro and in vivo tumor cell proliferation, tumorigenesis and chemoresistance. Knockout (KO) of VTRNA1-1 in human hepatocellular carcinoma cells reduced nuclear localization of TFEB (transcription factor EB), leading to a downregulation of the coordinated lysosomal expression and regulation (CLEAR) network genes and lysosomal compartment dysfunction. We demonstrate further that impaired lysosome function due to loss of VTRNA1-1 potentiates the anticancer effect of conventional chemotherapeutic drugs. Finally, loss of VTRNA1-1 reduced drug lysosomotropism allowing higher intracellular compound availability and thereby significantly reducing tumor cell proliferation in vitro and in vivo. These findings reveal a so far unknown role of VTRNA1-1 in the intracellular catabolic compartment and describe its contribution to lysosome-mediated chemotherapy resistance.

Abbreviations: ATP6V0D2: ATPase H+ transporting V0 subunit d2; BafA: bafilomycin A1; CLEAR: coordinated lysosomal expression and regulation; CQ: chloroquine; DMSO: dimethyl sulfoxide; GST-BHMT: glutathionine S-transferase N-terminal to betaine–homocysteine S-methyltransferase; HCC: hepatocellular carcinoma; LAMP1: lysosomal associated membrane protein 1; LLOMe: L-leucyl-L-leucine methyl ester; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3 beta; MAPK: mitogen-activated protein kinase; MITF: melanocyte inducing transcription factor; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; ncRNA: non-coding RNA; RNP: ribonucleoprotein; SF: sorafenib; SQSTM1/p62: sequestosome 1; STS: staurosporine; tdRs: tRNA-derived RNAs; TFE3: transcription factor binding to IGHM enhancer 3; TFEB: transcription factor EB; vtRNA: vault RNA transcript.

Mitochondrial Dynamics, ROS, and Cell Signaling: A Blended Overview

Mitochondria are key intracellular organelles involved not only in the metabolic state of the cell, but also in several cellular functions, such as proliferation, Calcium signaling, and lipid trafficking. Indeed, these organelles are characterized by continuous events of fission and fusion which contribute to the dynamic plasticity of their network, also strongly influenced by mitochondrial contacts with other subcellular organelles. Nevertheless, mitochondria release a major amount of reactive oxygen species (ROS) inside eukaryotic cells, which are reported to mediate a plethora of both physiological and pathological cellular functions, such as growth and proliferation, regulation of autophagy, apoptosis, and metastasis. Therefore, targeting mitochondrial ROS could be a promising strategy to overcome and hinder the development of diseases such as cancer, where malignant cells, possessing a higher amount of ROS with respect to healthy ones, could be specifically targeted by therapeutic treatments. In this review, we collected the ultimate findings on the blended interplay among mitochondrial shaping, mitochondrial ROS, and several signaling pathways, in order to contribute to the dissection of intracellular molecular mechanisms involved in the pathophysiology of eukaryotic cells, possibly improving future therapeutic approaches.

Autophagy Regulation and Photodynamic Therapy: Insights to Improve Outcomes of Cancer Treatment

Cancer is considered an age-related disease that, over the next 10 years, will become the most prevalent health problem worldwide. Although cancer therapy has remarkably improved in the last few decades, novel treatment concepts are needed to defeat this disease. Photodynamic Therapy (PDT) signalize a pathway to treat and manage several types of cancer. Over the past three decades, new light sources and photosensitizers (PS) have been developed to be applied in PDT. Nevertheless, there is a lack of knowledge to explain the main biochemical routes needed to trigger regulated cell death mechanisms, affecting, considerably, the scope of the PDT. Although autophagy modulation is being raised as an interesting strategy to be used in cancer therapy, the main aspects referring to the autophagy role over cell succumbing PDT-photoinduced damage remain elusive. Several reports emphasize cytoprotective autophagy, as an ultimate attempt of cells to cope with the photo-induced stress and to survive. Moreover, other underlying molecular mechanisms that evoke PDT-resistance of tumor cells were considered. We reviewed the paradigm about the PDT-regulated cell death mechanisms that involve autophagic impairment or boosted activation. To comprise the autophagy-targeted PDT-protocols to treat cancer, it was underlined those that alleviate or intensify PDT-resistance of tumor cells. Thereby, this review provides insights into the mechanisms by which PDT can be used to modulate autophagy and emphasizes how this field represents a promising therapeutic strategy for cancer treatment.

5-aminolevulinic acid-mediated photodynamic therapy can target aggressive adult T cell leukemia/lymphoma resistant to conventional chemotherapy

Photodynamic therapy (PDT) is an emerging treatment for various solid cancers. We recently reported that tumor cell lines and patient specimens from adult T cell leukemia/lymphoma (ATL) are susceptible to specific cell death by visible light exposure after a short-term culture with 5-aminolevulinic acid, indicating that extracorporeal photopheresis could eradicate hematological tumor cells circulating in peripheral blood. As a bridge from basic research to clinical trial of PDT for hematological malignancies, we here examined the efficacy of ALA-PDT on various lymphoid malignancies with circulating tumor cells in peripheral blood. We also examined the effects of ALA-PDT on tumor cells before and after conventional chemotherapy. With 16 primary blood samples from 13 patients, we demonstrated that PDT efficiently killed tumor cells without influencing normal lymphocytes in aggressive diseases such as acute ATL. Importantly, PDT could eradicate acute ATL cells remaining after standard chemotherapy or anti-CCR4 antibody, suggesting that PDT could work together with other conventional therapies in a complementary manner. The responses of PDT on indolent tumor cells were various but were clearly depending on accumulation of protoporphyrin IX, which indicates the possibility of biomarker-guided application of PDT. These findings provide important information for developing novel therapeutic strategy for hematological malignancies.

Looking Inside the World of Granulosa Cells: The Noxious Effects of Cigarette Smoke

The detrimental implications of tobacco smoke on systemic health have been widely established during the past few decades. Nonetheless, increasing evidence has begun to shed more light on the serious impact that smoke exposure could also have on mammal reproductive health in terms of overall ovarian dysfunction and gestation. A variety of these complications seem to be causally related to specific chemical substances contained in cigarette smoke and their possible effects on ovarian tissues and cells, such as granulosa cells. Granulosa cells represent the functional unit of the ovary and are able to establish a bidirectional cross-talk relationship with the oocyte during folliculogenesis, which makes them vital for its correct growth and development. Based on these premises, the current review focuses on the presence of related smoke-induced damages in granulosa cells. Data have been grouped according to the studied tobacco constituents and the molecular pathways involved, in order to synthesize their impact on granulosa cells and fertility. Attention is further brought to the correlation between electronic cigarettes and female reproduction, although there have been no investigations so far regarding e-cigarette-related granulosa cell exposure. We summarize how tobacco constituents are able to cause alterations in the "life" of granulosa cells, ranging from luteal steroidogenesis and follicular loss to granulosa cell apoptosis and activation of the autophagic machinery. Further studies have been conducted to elucidate the relationship between lifestyle and fertility as to reduce the morbidity connected with infertility.

CHK2-FOXK axis promotes transcriptional control of autophagy programs

Autophagy is an evolutionarily conserved catabolic process, which plays a vital role in removing misfolded proteins and clearing damaged organelles to maintain internal environment homeostasis. Here, we uncovered the checkpoint kinase 2 (CHK2)-FOXK (FOXK1 and FOXK2) axis playing an important role in DNA damage-mediated autophagy at the transcriptional regulation layer. Mechanistically, following DNA damage, CHK2 phosphorylates FOXK and creates a 14-3-3γ binding site, which, in turn, traps FOXK proteins in the cytoplasm. Because FOXK functions as the transcription suppressor of ATGs, DNA damage-mediated FOXKs' cytoplasmic trapping induces autophagy. In addition, we found that a cancer-derived FOXK mutation induces FOXK hyperphosphorylation and enhances autophagy, resulting in chemoresistance. Cotreatment with cisplatin and chloroquine overcomes the chemoresistance caused by FOXK mutation. Overall, our study highlights a mechanism whereby DNA damage triggers autophagy by increasing autophagy genes via CHK2-FOXK-mediated transcriptional control, and misregulation of this pathway contributes to chemoresistance.

Berberine associated photodynamic therapy promotes autophagy and apoptosis via ROS generation in renal carcinoma cells

Renal cell carcinoma (RCC) consists of the most lethal common urological cancer and the clinical practice has shown that resistant RCC to commons therapies is extremely high. Berberine is an isoquinoline alkaloid, presents in different kinds of plants and it has long been used in Chinese medicine. It has several properties, such as antioxidant, anti-inflammatory, anti-diabetic, anti-microbial and anti-cancer. Moreover, berberine has photosensitive characteristics and its association with photodynamic therapy (PDT) is effective against tumor cells. This study aimed to evaluate the effects of berberine associated with PDT in renal carcinoma cell lines. The cellular viability assay showed increased cytotoxicity in concentration and time-dependent manner. Berberine presented efficient internalization in all cell lines analyzed. In addition, after treatment with berberine associated with PDT, it was observed a high phototoxicity effect with less than 20 % of viable cells. In this study we observed that the increase of reactive oxygen species (ROS) levels was accompanied by an increase of autophagy levels and apoptosis by caspase 3 activity, suggesting cell death by both mechanisms. Additionally, three target genes of anti-cancer drugs were differentially expressed in 786-O cells, being that Vascular Endothelial Growth Factor-D (FIGF) and Human Telomerase Reverse Transcriptase (TERT) gene presented low expression and Polo Like Kinase 3 (PLK3) presented overexpression after treatment with berberine associated with PDT. In this study, the proposed treatment triggered metabolites changes related to cell proliferation, tumorigenesis and angiogenesis. Thus, it was possible to suggest that berberine has promising potential as a photosensitizing agent in a photodynamic therapy, because it induced significant anticancer effects on renal carcinoma cells.

The Course of Immune Stimulation by Photodynamic Therapy: Bridging Fundamentals of Photochemically Induced Immunogenic Cell Death to the Enrichment of T-Cell Repertoire

Photodynamic therapy (PDT) is a potentially immunogenic and FDA-approved antitumor treatment modality that utilizes the spatiotemporal combination of a photosensitizer, light and oftentimes oxygen, to generate therapeutic cytotoxic molecules. Certain photosensitizers under specific conditions, including ones in clinical practice, have been shown to elicit an immune response following photoillumination. When localized within tumor tissue, photogenerated cytotoxic molecules can lead to immunogenic cell death (ICD) of tumor cells, which release damage-associated molecular patterns and tumor-specific antigens. Subsequently, the T-lymphocyte (T cell)-mediated adaptive immune system can become activated. Activated T cells then disseminate into systemic circulation and can eliminate primary and metastatic tumors. In this review, we will detail the multistage cascade of events following PDT of solid tumors that ultimately lead to the activation of an antitumor immune response. More specifically, we connect the fundamentals of photochemically induced ICD with a proposition on potential mechanisms for PDT enhancement of the adaptive antitumor response. We postulate a hypothesis that during the course of the immune stimulation process, PDT also enriches the T-cell repertoire with tumor-reactive activated T cells, diversifying their tumor-specific targets and eliciting a more expansive and rigorous antitumor response. The implications of such a process are likely to impact the outcomes of rational combinations with immune checkpoint blockade, warranting investigations into T-cell diversity as a previously understudied and potentially transformative paradigm in antitumor photodynamic immunotherapy.

Endoplasmic Reticulum Stress Signaling Pathways: Activation and Diseases

Secretory and membrane proteins are folded in the endoplasmic reticulum (ER) prior to their exit. When ER function is disturbed by exogenous and endogenous factors, such as heat shock, ultraviolet radiation, hypoxia, or hypoglycemia, the misfolded proteins may accumulate, promoting ER stress. To rescue this unfavorable situation, the unfolded protein response is activated to reduce misfolded proteins within the ER. Upon ER stress, the ER transmembrane sensor molecules inositol-requiring enzyme 1 (IRE1), RNA-dependent protein kinase (PKR)-like ER kinase (PERK), and activating transcription factor 6, are activated. Here, we discuss the mechanisms of PERK and IRE1 activation and describe two working models for ER stress initiation: the BiP-dependent model and the ligand-driven model. ER stress activation has been linked to multiple diseases, including cancers, Alzheimer's disease, and diabetes. Thus, the regulation of ER stress may provide potential therapeutic targets for these diseases.

Identification of the Apoptosis and Autophagy Bi-functional Proteins

Although autophagy and apoptosis, two main kinds of programmed cell death, constitute distinct cellular processes with often opposing outcomes, there have been shown a complex interplay between them in recent years. This interplay is surely critical to the overall fate of the cell. However, a full-scale identification of those bi-functional proteins involved in both functions is currently beyond reach by existing databases or traditional biological experiments. And that makes the interplay impossible to be well understood. Here we built a large, comprehensiveness apoptosis and autophagy related PPI (protein-protein interaction) network and then used topology clustering to undergo a network analysis workflow. Finally, we concluded a list of 151 apoptosis and autophagy bi-functional proteins from this network. By this way we showed a global view on these bi-functional proteins about their unique characteristics and provided clues of new functions of some proteins which are not focused in present researches.

Comparison of Cellular Death Pathways after mTHPC-mediated Photodynamic Therapy (PDT) in Five Human Cancer Cell Lines

One of the most promising photosensitizers (PS) used in photodynamic therapy (PDT) is the porphyrin derivative 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC, temoporfin), marketed in Europe under the trade name Foscan^®. A set of five human cancer cell lines from head and neck and other PDT-relevant tissues was used to investigate oxidative stress and underlying cell death mechanisms of mTHPC-mediated PDT in vitro. Cells were treated with mTHPC in equitoxic concentrations and illuminated with light doses of 1.8-7.0 J/cm² and harvested immediately, 6, 24, or 48 h post illumination for analyses. Our results confirm the induction of oxidative stress after mTHPC-based PDT by detecting a total loss of mitochondrial membrane potential (Δψ_m) and increased formation of ROS. However, lipid peroxidation (LPO) and loss of cell membrane integrity play only a minor role in cell death in most cell lines. Based on our results, apoptosis is the predominant death mechanism following mTHPC-mediated PDT. Autophagy can occur in parallel to apoptosis or the former can be dominant first, yet ultimately leading to autophagy-associated apoptosis. The death of the cells is in some cases accompanied by DNA fragmentation and a G₂/M phase arrest. In general, the overall phototoxic effects and the concentrations as well as the time to establish these effects varies between cell lines, suggesting that the cancer cells are not all dying by one defined mechanism, but rather succumb to an individual interplay of different cell death mechanisms. Besides the evaluation of the underlying cell death mechanisms, we focused on the comparison of results in a set of five identically treated cell lines in this study. Although cells were treated under equitoxic conditions and PDT acts via a rather unspecific ROS formation, very heterogeneous results were obtained with different cell lines. This study shows that general conclusions after PDT in vitro require testing on several cell lines to be reliable, which has too often been ignored in the past.

Parallel damage in mitochondria and lysosomes is an efficient way to photoinduce cell death

Cells challenged by photosensitized oxidations face strong redox stresses and rely on autophagy to either survive or die. However, the use of macroautophagy/autophagy to improve the efficiency of photosensitizers, in terms of inducing cell death, remains unexplored. Here, we addressed the concept that a parallel damage in the membranes of mitochondria and lysosomes leads to a scenario of autophagy malfunction that can greatly improve the efficiency of the photosensitizer to cause cell death. Specific damage to these organelles was induced by irradiation of cells pretreated with 2 phenothiazinium salts, methylene blue (MB) and 1,9-dimethyl methylene blue (DMMB). At a low concentration level (10 nM), only DMMB could induce mitochondrial damage, leading to mitophagy activation, which did not progress to completion because of the parallel damage in lysosome, triggering cell death. MB-induced photodamage was perceived almost instantaneously after irradiation, in response to a massive and nonspecific oxidative stress at a higher concentration range (2 µM). We showed that the parallel damage in mitochondria and lysosomes activates and inhibits mitophagy, leading to a late and more efficient cell death, offering significant advantage (2 orders of magnitude) over photosensitizers that cause unspecific oxidative stress. We are confident that this concept can be used to develop better light-activated drugs. Abbreviations: ΔΨm: mitochondrial transmembrane inner potential; AAU: autophagy arbitrary units; ATG5, autophagy related 5; ATG7: autophagy related 7; BAF: bafilomycin A1; BSA: bovine serum albumin; CASP3: caspase 3; CF: carboxyfluorescein; CTSB: cathepsin B; CVS: crystal violet staining; DCF: dichlorofluorescein; DCFH2: 2',7'-dichlorodihydrofluorescein; DMMB: 1,9-dimethyl methylene blue; ER: endoplasmic reticulum; HaCaT: non-malignant immortal keratinocyte cell line from adult human skin; HP: hydrogen peroxide; LC3B-II: microtubule associated protein 1 light chain 3 beta-II; LMP: lysosomal membrane permeabilization; LTG: LysoTracker™ Green DND-26; LTR: LysoTracker™ Red DND-99; 3-MA: 3-methyladenine; MB: methylene blue; mtDNA: mitochondrial DNA; MitoSOX™: red mitochondrial superoxide probe; MTDR: MitoTracker™ Deep Red FM; MTO: MitoTracker™ Orange CMTMRos; MT-ND1: mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 1; MTT: methylthiazolyldiphenyl-tetrazolium bromide; 1O2: singlet oxygen; OH. hydroxil radical; PRKN/parkin: parkin RBR E3 ubiquitin protein ligase; PBS: phosphate-buffered saline; PI: propidium iodide; PDT: photodynamic therapy; PS: photosensitizer; QPCR: gene-specific quantitative PCR-based; Rh123: rhodamine 123; ROS: reactive oxygen species RTN: rotenone; SQSTM1/p62: sequestosome 1; SUVs: small unilamellar vesicles; TBS: Tris-buffered saline.

Ancistrolikokine E3, a 5,8'-Coupled Naphthylisoquinoline Alkaloid, Eliminates the Tolerance of Cancer Cells to Nutrition Starvation by Inhibition of the Akt/mTOR/Autophagy Signaling Pathway

PANC-1 human pancreatic cancer cells are characterized by their ability to proliferate aggressively under hypovascular and hypoxic conditions in the tumor microenvironment, displaying a remarkable tolerance to nutrition starvation. The antiausterity strategy is a new approach in anticancer drug discovery aiming at the identification of potent agents that inhibit preferentially the survival of tumor cells during a limited supply of nutrients and oxygen. The new 5,8'-coupled naphthyldihydroisoquinoline alkaloid ancistrolikokine E₃ (4), isolated from the Congolese liana Ancistrocladus likoko, showed potent preferential cytotoxicity against PANC-1 cells under nutrient-deprived conditions, with a PC₅₀ value of 2.5 μM, without exhibiting toxicity in normal, nutrient-rich medium. The compound was found to induce dramatic alterations in cell morphology, leading to cell death. Moreover, it inhibited significantly PANC-1 cell migration and colony formation in a concentration-dependent manner. This study on 4 provides the first live evidence of the effect of a naphthyldihydroisoquinoline alkaloid against PANC-1 cells in nutrient-deprived medium. Mechanistic investigations conducted suggest that compound 4 is a potent inhibitor of the activation of the Akt/mTOR pathway. Furthermore, it inhibited the expression levels of the key autophagy regulators Atg5, Atg12, Beclin-1, LC3-I, and LC3-II. The results demonstrated that ancistrolikokine E₃ (4) is a potent early-stage inhibitor of the autophagy pathway in PANC-1 human pancreatic cancer cells. Ancistrolikokine E₃ (4) and related naphthylisoquinoline alkaloids are promising potential lead compounds for anticancer drug development based on the antiausterity strategy.

Photosensitizer and Autophagy Promoter Coloaded ROS-Responsive Dendrimer-Assembled Carrier for Synergistic Enhancement of Tumor Growth Suppression

Reactive oxygen species (ROS) generated during photodynamic therapy (PDT) can trigger autophagy. However, little research is focused on whether there is a synergistic anticancer effect with PDT if extra autophagy promoter or inhibitor is added. Here, it is found that autophagy promotion significantly enhances the PDT activity to cancer cells. Based on this preliminary result, a ROS-sensitive self-assembled dendrimer nanoparticle is exploited as a carrier to codeliver an autophagy promoter (rapamycin, Rapa) and photosensitizer (phthalocyanine, Pc) to the tumor. After entrapped by cancer cells and irradiated by light, the ROS generated in PDT process of Pc can trigger nanoparticle destruction to release Rapa, thus initiating the autophagy process and remarkably enhancing the efficacy of PDT, leading to efficient tumor suppression.

Pre-drug Self-assembled Nanoparticles: Recovering activity and overcoming glutathione-associated cell antioxidant resistance against photodynamic therapy

In photodynamic therapy (PDT), the elevated glutathione (GSH) of cancer cells have two sides for treatment efficacy, activation pre-drug by removing activity suppressor part (advantages) and consumption reactive oxygen species (ROS) to confer PDT resistance (disadvantages). Preparation all-in-one system by simple method to make best use of the advantages and bypass the disadvantages still were remains a technical challenge. Herein, we report a robust PDT nanoparticle with above function based on a self-assembled pyridine modified Zinc phthalocyanine (ZnPc-DTP). The activity suppressor and active part of ZnPc-DTP were linked by disulfide bond. After targeting cancer cells, GSH can react with ZnPc-DTP nanoparticles by cutting disulfide bond to release its active part (ZnPc-SH) and oxidize GSH. In vitro and in vivo results indicated that ZnPc-SH can effective suppress tumor growth under the low antioxidant tumor microenvironment (TME).

Insight into ultrasound-mediated reactive oxygen species generation by various metal-porphyrin complexes

Ultrasound is used to trigger the cytotoxicity of chemical compounds, known as sonosensitisers, in an approach called sonodynamic therapy (SDT), which is under investigation herein. The generation of reactive oxygen species (ROS) has been proposed as the main biological occurrence that leads to the cytotoxic effects, which are achieved via the synergistic action of two components: the energy-absorbing sonosensitiser and ultrasound (US), which are both harmless per se. Despite some promising results, a lack of investigation into the mechanisms behind US sonosensitiser-mediated ROS generation has prevented SDT from reaching its full potential. The aim of this work is to investigate the US-responsiveness of a variety of metal-porphyrin complexes, free-base porphyrin and Fe(III), Zn(II) and Pd(II) porphyrin, by analyzing their ROS generation under US exposure and related bio-effects. All experiments were also carried out under light exposure and the results were used as references. Our results show that porphyrin ultrasound-responsiveness depends on the metal ion present, with Zn(II) and Pd(II) porphyrin being the most efficient in generating singlet oxygen and hydroxyl radicals. ROS production efficiency is lower after ultrasound exposure than after light exposure, because of the various physico-chemical mechanisms involved in sensitiser activation. US and porphyrin-mediated ROS generation is oxygen-dependent and the activation of porphyrin by US appears to be more compatible with sonoluminescence-based photo-activation rather than a radical path process that occurs via the homolytic bond rupture of water. Notably, the cytotoxicity results reported herein, which are mirrored by ex-cellulo data, confirm that the type of ROS generation achieved by the US activation of intracellular porphyrins is pivotal to the effectiveness of cancer cell killing.

Autophagy-associated immune responses and cancer immunotherapy

Autophagy is an evolutionarily conserved catabolic process by which cellular components are sequestered into a double-membrane vesicle and delivered to the lysosome for terminal degradation and recycling. Accumulating evidence suggests that autophagy plays a critical role in cell survival, senescence and homeostasis, and its dysregulation is associated with a variety of diseases including cancer, cardiovascular disease, neurodegeneration. Recent studies show that autophagy is also an important regulator of cell immune response. However, the mechanism by which autophagy regulates tumor immune responses remains elusive. In this review, we will describe the role of autophagy in immune regulation and summarize the possible molecular mechanisms that are currently well documented in the ability of autophagy to control cell immune response. In addition, the scientific and clinical hurdles regarding the potential role of autophagy in cancer immunotherapy will be discussed.

Apoptosis and autophagy induced by pyropheophorbide-α methyl ester-mediated photodynamic therapy in human osteosarcoma MG-63 cells

Pyropheophorbide-α methyl ester (MPPa) was a second-generation photosensitizer with many potential applications. Here, we explored the impact of MPPa-mediated photodynamic therapy (MPPa-PDT) on the apoptosis and autophagy of human osteosarcoma (MG-63) cells as well as the relationships between apoptosis and autophagy of the cells, and investigated the related molecular mechanisms. We found that MPPa-PDT demonstrated the ability to inhibit MG-63 cell viability in an MPPa concentration- and light dose-dependent manner, and to induce apoptosis via the mitochondrial apoptosis pathway. Additionally, MPPa-PDT could also induce autophagy of MG-63 cell. Meanwhile, the ROS scavenger N-acetyl-l-cysteine (NAC) and the Jnk inhibitor SP600125 were found to inhibit the MPPa-PDT-induced autophagy, and NAC could also inhibit Jnk phosphorylation. Furthermore, pretreatment with the autophagy inhibitor 3-methyladenine or chloroquine showed the potential in reducing the apoptosis rate induced by MPPa-PDT in MG-63 cells. Our results indicated that the mitochondrial pathway was involved in MPPa-PDT-induced apoptosis of MG-63 cells. Meanwhile the ROS-Jnk signaling pathway was involved in MPPa-PDT-induced autophagy, which further promoted the apoptosis in MG-63 cells.

Regulation of Autophagy by MiRNAs and Their Emerging Roles in Tumorigenesis and Cancer Treatment

Autophagy is a conserved catabolic process for the degradation and recycling of cytosolic components or organelles through a lysosome-dependent pathway. Autophagy can be induced in response to multiple stress conditions, such as nutrient deprivation, hypoxia, energy depletion, etc. As a result, autophagy can regulate many biological processes, including cell survival, metabolism, differentiation, senescence, and cell death. MicroRNAs (MiRNAs) are small noncoding molecules that regulate gene expression by silencing mRNA targets. MiRNA dysregulation exhibits great regulatory potential during organismal development, hematopoiesis, immunity, cell proliferation and death, and autophagy. Recently, increasing studies have linked MiRNAs to autophagic regulation during cancer initiation and development. Although the relationship between MiRNAs and autophagy is quite complicated and has not been well elucidated, MiRNAs may underlie key aspects of autophagy and cancer biology. Increasing evidence shows that MiRNAs play important roles as both oncogenic MiRNAs and tumor suppressive MiRNAs in cancer initiation and development. Thus, understanding the novel relationship between MiRNAs and autophagy may allow us to develop promising cancer biomarkers and therapeutic targets.

Autophagy is required for crizotinib-induced apoptosis in MET-amplified gastric cancer cells

MET amplification has been clinically credentialed as a therapeutic target in gastric cancer, but the molecular mechanisms underlying sensitivity and resistance to MET inhibitors are still not well understood. Using whole-genome mRNA expression profiling, we identified autophagy as a top molecular pathway that was activated by the MET inhibitor crizotinib in drug-sensitive human gastric cancer cells, and functional studies confirmed that crizotinib increased autophagy levels in the drug-sensitive cells in a concentration-dependent manner. We then used chemical and molecular approaches to inhibit autophagy in order to define its role in cell death. The clinically available inhibitor of autophagy, chloroquine, or RNAi-mediated knockdown of two obligate components of the autophagy pathway (ATG5 and ATG7) blocked cell death induced by crizotinib or RNAi-mediated knockdown of MET, and mechanistic studies localized the effects of autophagy to cytochrome c release from the mitochondria. Overall, the data reveal a novel relationship between autophagy and apoptosis in gastric cancer cells exposed to MET inhibitors. The observations suggest that autophagy inhibitors should not be used to enhance the effects of MET inhibitors in gastric cancer patients.

Porphyrin-based cationic amphiphilic photosensitisers as potential anticancer, antimicrobial and immunosuppressive agents

Photodynamic therapy (PDT) combines a photosensitiser, light and molecular oxygen to induce oxidative stress that can be used to kill pathogens, cancer cells and other highly proliferative cells. There is a growing number of clinically approved photosensitisers and applications of PDT, whose main advantages include the possibility of selective targeting, localised action and stimulation of the immune responses. Further improvements and broader use of PDT could be accomplished by designing new photosensitisers with increased selectivity and bioavailability. Porphyrin-based photosensitisers with amphiphilic properties, bearing one or more positive charges, are an effective tool in PDT against cancers, microbial infections and, most recently, autoimmune skin disorders. The aim of the review is to present some of the recent examples of the applications and research that employ this specific group of photosensitisers. Furthermore, we will highlight the link between their structural characteristics and PDT efficiency, which will be helpful as guidelines for rational design and evaluation of new PSs.

Synergistic efficacy of ultrasound, sonosensitizers and chemotherapy: a review

Chemotherapeutic agents, either in the form of systemically injected free drug or encapsulated in nanoparticles transport vehicles, must overcome three main obstacles prior to reaching and interacting with their intended target inside tumor cells. Drugs must leave the circulation, overcome the tissue-tumor barrier and penetrate the cell's plasma membrane. Since, many agents enter the cell by endocytosis, they must avoid entrapment and degradation by the intracellular endolysosome complex. Ultrasound has demonstrated potential to enhance the efficacy of chemotherapy by reducing these barriers. The purpose of this review is to highlight the potential of ultrasound in combination with sonosensitizers to enhance the efficacy of chemotherapy by optimizing the anticancer agent's intracellular ability to engage and interact with its target.

Photodynamic therapy enhances the efficacy of gene-directed enzyme prodrug therapy

INTRODUCTION

Gene-directed enzyme prodrug therapy (GDEPT) employing the cytosine deaminase (CD) gene, which encodes an enzyme that converts the nontoxic agent 5-fluorocytosine (5-FC) into the chemotherapeutic drug 5-fluorouracil (5-FU), has shown promise both in experimental animals and in clinical trials. Nevertheless, with the transfection systems available presently the percentage of tumor cells incorporating the desired gene is usually too low for successful therapy. We have examined the ability of photodynamic therapy (PDT) to enhance the efficacy of the metabolites, converted from 5-FC by CD gene transfected rat glioma cells.

METHODS

Hybrid tumor cell spheroids consisting of CD poitive and CD negative F98 glioma cells in varying ratios were used as in vitro tumor models. PDT was performed with the photosensitizer AlPcS_2a and λ=670nm laser irradiance, both before and after confrontation with 5-FC.

RESULTS

PDT increased the toxicity of 5-FU either as pure drug or derived from monolayers of CD positive cells chalanged with 5-FC. PDT in combination with 5-FC resulted in a significantly enhanced inhibition of hybrid spheroid growth compared to non light treated controls. This was the case even at tumor to producer cell ratios as high as 40:1.

CONCLUSION

The results of the present study show that GDEPT and PDT interact in a synergistic manner over a range of prodrug concentration and tumor to transfected cell ratios. The degree of synergy was significant regardless if PDT treatment was given before or after 5-FC administration. The highest degree of interaction was observed though, when PDT was delivered prior to prodrug exposure.

Regulation of autophagy by some natural products as a potential therapeutic strategy for cardiovascular disorders

Autophagy is a lysosomal degradation process through which long-lived and misfolded proteins and organelles are sequestered, degraded by lysosomes, and recycled. Autophagy is an essential part of cardiomyocyte homeostasis and increases the survival of cells following cellular stress and starvation. Recent studies made clear that dysregulation of autophagy in the cardiovascular system leads to heart hypertrophy and failure. In this manner, autophagy seems to be an attractive target in the new treatment of cardiovascular diseases. Although limited activation of autophagy is generally considered to be cardioprotective, excessive autophagy leads to cell death and cardiac atrophy. Natural products such as resveratrol, berberine, and curcumin that are present in our diet, can trigger autophagy via canonical (Beclin-1-dependent) and non-canonical (Beclin-1-independent) pathways. The autophagy-modifying capacity of these compounds should be taken into consideration for designing novel therapeutic agents. This review focuses on the role of autophagy in the cardioprotective effects of these compounds.

Oncologic Photodynamic Therapy: Basic Principles, Current Clinical Status and Future Directions

Photodynamic therapy (PDT) is a clinically approved cancer therapy, based on a photochemical reaction between a light activatable molecule or photosensitizer, light, and molecular oxygen. When these three harmless components are present together, reactive oxygen species are formed. These can directly damage cells and/or vasculature, and induce inflammatory and immune responses. PDT is a two-stage procedure, which starts with photosensitizer administration followed by a locally directed light exposure, with the aim of confined tumor destruction. Since its regulatory approval, over 30 years ago, PDT has been the subject of numerous studies and has proven to be an effective form of cancer therapy. This review provides an overview of the clinical trials conducted over the last 10 years, illustrating how PDT is applied in the clinic today. Furthermore, examples from ongoing clinical trials and the most recent preclinical studies are presented, to show the directions, in which PDT is headed, in the near and distant future. Despite the clinical success reported, PDT is still currently underutilized in the clinic. We also discuss the factors that hamper the exploration of this effective therapy and what should be changed to render it a more effective and more widely available option for patients.

The potential of photodynamic therapy (PDT)-Experimental investigations and clinical use

Photodynamic therapy (PDT) is an intensively studied part of medicine based on free radicals. These reactive species, extremely harmful for whole human organism, are used for eradication numerous diseases. Specific structure of ill tissues causes accumulation free radicals inside them without attack remaining healthy tissues. A rapid development of medicine and scientific research has led to extension of PDT towards treatment many diseases such as cancer, herpes, acne and based on antimicrobials. The presented review article is focused on the aforementioned disorders with accurate analysis of the newest available scientific achievements. The discussed cases explicitly indicate on high efficacy of the therapy. In most cases, free radicals turned out to be solution of many afflictions. Photodynamic therapy can be considered as promising treatment with comparable effectiveness but without side effects characteristic for chemotherapy.

A Versatile Imaging and Therapeutic Platform Based on Dual-Band Luminescent Lanthanide Nanoparticles toward Tumor Metastasis Inhibition

Upconversion (UC) luminescent lanthanide nanoparticles (LNPs) are expected to play an important role in imaging and photodynamic therapy (PDT) in vitro and in vivo. However, with the absorption of UC emissions by photosensitizers (PSs) to generate singlet oxygen ((1)O2) for PDT, the imaging signals from LNPs are significantly weakened. It is important to activate another imaging route to track the location of the LNPs during PDT process. In this work, Nd(3+)-sensitized LNPs with dual-band visible and near-infrared (NIR) emissions under single 808 nm excitation were reported to address this issue. The UC emissions in green could trigger covalently linked rose bengal (RB) molecules for efficient PDT, and NIR emissions deriving from Yb(3+) and magnetic resonance imaging (MRI) were used for imaging simultaneously. Notably, the designed therapeutic platform could further effectively avoid the overheating effect induced by the laser irradiation, due to the minimized absorption of biological media at around 808 nm. TdT-mediated dUTP nick end labeling (TUNEL) assay showed serious cell apoptosis in the tumor after PDT for 2 weeks, leading to an effective tumor inhibition rate of 67%. Benefit from the PDT, the tumor growth-induced liver and spleen burdens were largely attenuated, and the liver injury was also alleviated. More importantly, pulmonary and hepatic tumor metastases were significantly reduced after PDT. The Nd(3+)-sensitized LNPs provide a multifunctional nanoplatform for NIR light-assisted PDT with minimized heating effect and an effective inhibition of tumor growth and metastasis.

Autophagy-Modulated Human Bone Marrow-Derived Mesenchymal Stem Cells Accelerate Liver Restoration in Mouse Models of Acute Liver Failure

Background:

Mesenchymal stem cells (MSCs) have been recently received increasing attention for cell-based therapy, especially in regenerative medicine. However, the low survival rate of these cells restricts their therapeutic applications. It is hypothesized that autophagy might play an important role in cellular homeostasis and survival. This study aims to investigate the regenerative potentials of autophagy-modulated MSCs for the treatment of acute liver failure (ALF) in mice.

Methods:

ALF was induced in mice by intraperitoneal injection of 1.5 ml/kg carbon tetrachloride. Mice were intravenously infused with MSCs, which were suppressed in their autophagy pathway. Blood and liver samples were collected at different intervals (24, 48 and 72 h) after the transplantation of MSCs. Both the liver enzymes and tissue necrosis levels were evaluated using biochemical and histopathological assessments. The survival rate of the transplanted mice was also recorded during one week.

Results:

Biochemical and pathological results indicated that 1.5 ml/kg carbon tetrachloride induces ALF in mice. A significant reduction of liver enzymes and necrosis score were observed in autophagy-modulated MSC-transplanted mice compared to sham (with no cell therapy) after 24 h. After 72 h, liver enzymes reached their normal levels in mice transplanted with autophagy-suppressed MSCs. Interestingly, normal histology without necrosis was also observed.

Conclusion:

Autophagy suppression in MSCs ameliorates their liver regeneration potentials due to paracrine effects and might be suggested as a new strategy for the improvement of cell therapy in ALF.

Effects of HSP27 downregulation on PDT resistance through PDT-induced autophagy in head and neck cancer cells

We previously reported that photodynamic therapy (PDT) induces cell death in head and neck cancer through both autophagy and apoptosis. Regulation of cell death by autophagy and apoptosis is important to enhance the effects of PDT. Autophagy maintains a balance between cell death and PDT resistance. Downregulation of heat shock protein 27 (HSP27) induces PDT resistance in head and neck cancer cells. Furthermore, HSP70 regulates apoptosis during oxidative stress. However, the role of HSPs in PDT-induced cell death through autophagy and apoptosis is unclear. Therefore, in the present study, we investigated the effects of HSP27 and HSP70 on PDT-induced cell death of oral cancer cells through autophagy and apoptosis. Cancer cells were treated with hematoporphyrin at varying doses, followed by irradiation at 635 nm with an energy density of 5 mW/cm2. We determined the changes in HSP expression by determining the levels of PARP-1 and LC3II in PDT-resistant cells. Furthermore, we assessed cell death signaling after downregulating HSPs by transfecting specific siRNAs. We observed that PDT decreased HSP27 expression but increased HSP70 expression in the head and neck cancer cells. Treatment of cells with LC3II and PARP-1 inhibitors resulted in upregulation of HSP70 and HSP27 expression, respectively. Downregulation of HSP27 and HSP70 induced cell death and PDT resistance through autophagy and apoptosis. Moreover, downregulation of HSP27 in PDT-resistant cells resulted in enhanced survival. These results indicate that the regulation of HSP27 and HSP70 plays a principal role in increasing the effects of PDT by inducing autophagic and apoptotic cell death.

Cigarette smoke exposure triggers the autophagic cascade via activation of the AMPK pathway in mice

We previously demonstrated that cigarette smoke (CS) exposure decreases primordial follicle counts and induces autophagy in ovarian granulosa cells in preference to apoptosis. Therefore, the objective of this study was to investigate molecular targets underlying smoke-induced activation of the reparative autophagy pathway in the ovary. Briefly, ovarian homogenates were prepared from adult female mice exposed to mainstream CS twice daily for 8 wk, using a whole-body exposure system. A gene array revealed that CS exposure induced a greater than 2-fold significant increase in the expression of proautophagic genes Cdkn1b, Map1lc3a, Bad, and Sqstm1/p62. A significant increase in Prkaa2, Pik3c3, and Maplc31b expression, as well as a significant decrease in Akt1 and Mtor expression, was detected by quantitative PCR. The 5'-AMP-activated protein kinase catalytic subunit (AMPK) alpha1 + alpha2 and ATG7 protein expression was significantly increased, whereas AKT1, mTOR, CDKN1B/p27, and CXCR4 proteins were significantly decreased in CS exposed versus control ovaries. Up-regulation of AMPK alpha1 + alpha2, a known initiator of autophagic signaling, and ATG7 further suggests activation of the autophagy cascade. Two prosurvival factors, AKT and mTOR, were decreased in expression, an outcome that favors induction of the autophagy pathway, whereas decreased levels of CDKN1B is suggestive of cell cycle dysregulation. In summary, our data suggest that CS exposure induces ovarian follicle loss through induction of the autophagic cascade via the AMPK pathway together with inhibition of antiautophagic markers AKT and mTOR. We further postulate that toxicant-induced dysregulation of reparative autophagy is a novel pathway central to impaired follicle development and subfertility.

Photodynamic Efficiency: From Molecular Photochemistry to Cell Death

Photodynamic therapy (PDT) is a clinical modality used to treat cancer and infectious diseases. The main agent is the photosensitizer (PS), which is excited by light and converted to a triplet excited state. This latter species leads to the formation of singlet oxygen and radicals that oxidize biomolecules. The main motivation for this review is to suggest alternatives for achieving high-efficiency PDT protocols, by taking advantage of knowledge on the chemical and biological processes taking place during and after photosensitization. We defend that in order to obtain specific mechanisms of cell death and maximize PDT efficiency, PSes should oxidize specific molecular targets. We consider the role of subcellular localization, how PS photochemistry and photophysics can change according to its nanoenvironment, and how can all these trigger specific cell death mechanisms. We propose that in order to develop PSes that will cause a breakthrough enhancement in the efficiency of PDT, researchers should first consider tissue and intracellular localization, instead of trying to maximize singlet oxygen quantum yields in in vitro tests. In addition to this, we also indicate many open questions and challenges remaining in this field, hoping to encourage future research.

EGCG synergizes the therapeutic effect of cisplatin and oxaliplatin through autophagic pathway in human colorectal cancer cells

Application of the platinum-based chemotherapy for colorectal cancer is restricted due to its severe cytotoxic effects. In this study we used synergistic strategies by combining (-)-Epigallocatechin gallate (EGCG) with cisplatin or oxaliplatin to minimize the ill effects of platinum-based therapy. MTS assay was used to examine the effect of EGCG, cisplatin and oxaliplatin on the proliferation of human colorectal cancer DLD-1 and HT-29 cells. Autophagic process was evaluated by detection of LC3-II protein, autophagosome formation, and quantification of Acidic Vesicular. Treatment of DLD-1 and HT-29 cells with EGCG plus cisplatin or oxaliplatin showed a synergistic effect on inhibition of cell proliferation and induction of cell death. EGCG enhanced the effect of cisplatin and oxaliplatin-induced autophagy in DLD-1 and HT-29 cells, as characterized by the accumulation of LC3-II protein, the increase of acidic vesicular organelles (AVOs), and the formation of autophagosome. In addition, transfection of DLD-1 and HT-29 cells with siRNA against ATG genes reduced EGCG synergistic effect. Our findings suggest that combining EGCG with cisplatin or oxaliplatin could potentiate the cytotoxicity of cisplatin and oxaliplatin in colorectal cancer cells through autophagy related pathway.

Apoptosis and associated phenomena as a determinants of the efficacy of photodynamic therapy

Failure of neoplastic cells to respond to conventional chemotherapy is usually associated with factors that limit access of drugs to subcellular sites, differences in cell-cycle kinetics or mutations leading to loss of drug-activation pathways or other processes that govern response factors. For PDT, efficacy depends mainly on selective uptake of photosensitizers by neoplastic cells, oxygenation levels, the suitable direction of irradiation and the availability of pathways to cell death that are highly conserved among mammalian cell types. While it is possible to engineer PDT-resistant cell types, current evidence suggests that the major obstacles to cancer control relate to drug, light and oxygen distribution. This review discusses some of the factors that can govern PDT-induced cell death.

Fast and facile preparation of PEGylated graphene from graphene oxide by lysosome targeting delivery of photosensitizer to efficiently enhance photodynamic therapy

A fast, facile and mass production method was reported to obtain stable and disperse polyethylene glycol (PEG) modified nanographene (NGO-PEG). Branched polyethylenimine (BPEI) was used to modify the NGO-PEG (NGO-PEG-BPEI) for further application.

Nanomaterials and autophagy: new insights in cancer treatment

Autophagy represents a cell’s response to stress. It is an evolutionarily conserved process with diversified roles. Indeed, it controls intracellular homeostasis by degradation and/or recycling intracellular metabolic material, supplies energy, provides nutrients, eliminates cytotoxic materials and damaged proteins and organelles. Moreover, autophagy is involved in several diseases. Recent evidences support a relationship between several classes of nanomaterials and autophagy perturbation, both induction and blockade, in many biological models. In fact, the autophagic mechanism represents a common cellular response to nanomaterials. On the other hand, the dynamic nature of autophagy in cancer biology is an intriguing approach for cancer therapeutics, since during tumour development and therapy, autophagy has been reported to trigger both an early cell survival and a late cell death. The use of nanomaterials in cancer treatment to deliver chemotherapeutic drugs and target tumours is well known. Recently, autophagy modulation mediated by nanomaterials has become an appealing notion in nanomedicine therapeutics, since it can be exploited as adjuvant in chemotherapy or in the development of cancer vaccines or as a potential anti-cancer agent. Herein, we summarize the effects of nanomaterials on autophagic processes in cancer, also considering the therapeutic outcome of synergism between nanomaterials and autophagy to improve existing cancer therapies.